Process for producing cement using pretreated oil shale

Claim 1

IN THE PROCESS FOR THE PRODUCTION OF CEMENT BY HEATING AT ELEVATED TEMPERATURES A MIXTURE OF CALCAREOUS PARTICLE MATERIAL AND PREHEATED OIL SHALE PARTICLE MATERIAL, THE IMPROVEMENT WHICH COMPRISES CARRYING OUT THE HEATING WITH A PRETREATED OIL SHALE PARTICLE MATERIAL HAVING AN AVERAGE PARTICLE SIZE OF AT MOST ABOUT 10 MM. IN DIAMETER, SAID OIL SHALE PARTICLE MATERIAL BEFORE BEING PRETREATED CONTAINING OXIDIZABLE OIL CONSTITUENTS INCLUDING CONSTITUENTS WHICH ARE READILY VOLATILE AND COMBUSTIBLE AT A TEMPERATURE OF FROM ABOUT 400 TO 650*C., THE REMAINING CONSTITUENTS THEREOF BEING DIFFICULTY VOLATILE YET COKABLE AT SAID TEMPERATURE OF FROM ABOUT 400 TO 650* C., SAID OIL SHALE PARTICLE MATERIAL BEING PRETREATED TO REMOVE SUBSTANTIALLY COMPLETELY ALL OF THE READILY VOLATILE CONSTITUENTS THEREOF BY COMPLETE COMBUSTION WITHOUT DISTILLATION BY THE STEP OF FLUIDIZED BED PARTIAL OXIDATION HEAT TREATMENT AT A TEMPERATURE OF FROM ABOUT 400 TO 650*C. IN THE PRESENCE OF A REDUCED OXYGEN SUPPLY BASED ON THE TOTAL OXIDIZABLE OIL CONSTITUENTS PRESENT IN THE OIL SHALE PARTICLE MATERIAL SUFFICIENT TO CAUSE BY SUCH REDUCED OXYGEN SUPPLY SUBSTANTIALLY COMPLETE COMBUSTION OF SUBSTANTIALLY ALL OF THE READILY VOLATILE OIL CONSTITUENTS THEREOF AND ONLY COKING WITHOUT SUBSTANTIALLY ANY COMBUSTION OF THE REMAINING DIFFICULTLY VOLATILE OIL CONSTITUENTS THEREOF.